We have a deployment with what I would call an Enterprise Cloud Provider. It's VMWare Infrastructure 3.5.x and includes VMotion / VMWare HA instances, etc.

At Provider 1 VMWare Tools was installed:

vmware-guestd is running and;

at least two kernel modules are loaded, vmmemctl & vmhgfs

Provider 1 does nightly VM Snapshots.

We are beginning a new deployment at Provider 2 (also an Enterprise Cloud Provider). They did not install VMWare Tools. Provider 2 does not do nightly VM Snapshots but rather file-system backups (using an agent).

From my reading it seems like at the very least VMWare Tools should be installed for the Memory Balloon Driver (vmmemctl) and from reading sources like this one it suggests that certain VirtualCenter management operations also depend upon VMWare Tools being installed in the Linux guest.

Note that all of our instances are headless (default runlevel is 3) and RHEL.

It is hard to find authoritative information on this question and the aforementioned source is somewhat dated.

Can someone shed some light on this? What are the factors/criteria that would lead to an answer in the affirmative or negative?

Heard back from Provider 2. They have essentially admitted an oversight (FML). In a VirtualCenter deploy VMWare Tools should definitely be installed, even in headless Linux guests. (Selecting as best answer since it was the closest.)
– HTTP500Jan 21 '11 at 17:27

Thanks for your reply. With regard to timekeeping though VMWare best practices are to use NTP not VMWare Tools. kb.vmware.com/selfservice/microsites/… "In all cases use NTP instead of VMware Tools periodic time synchronization."
– HTTP500Jan 18 '11 at 21:11

@Jason -- Do you know if that's a recent new recommendation? I could swear that an earlier version of that document said the opposite, but it's possible I'm mis-remembering.
– larsksJan 18 '11 at 21:41

3

@larsks, using NTP it is a somewhat new recontamination. I noticed the change a few months ago.
– ZoredacheJan 18 '11 at 21:47

In addition to the better power/cpu/memory management that other answers have mentioned, the tools also give you the vmxnet* and pvscsi/something else/ device drivers that, ostensibly, provide better performance for networking and IO compared to emulating a "real" device.

In modern times it is better to install open-vm-tools, e.g. on Debian or Ubuntu:

apt-get install open-vm-tools

From the package description:

The Open Virtual Machine Tools (open-vm-tools) project is an open source
implementation of VMware Tools. It is a suite of virtualization utilities and
drivers to improve the functionality, user experience and administration of
VMware virtual machines.